FBI chief says Americans could be learning terrorism in Syria

Flags of the al Qaeda-linked Islamic State of Iraq and the Levant are hung on The Martyrs Church in Raqqa, Syria, on Sept. 27.

FBI Director James Comey says the prospect of Americans going to Syria, learning terrorist techniques and returning to the United States is one of his greatest worries.

"We are devoting more resources both to that subject and to that area," he said Thursday during a question-and-answer session with reporters. "We have a robust effort under way to figure out who has been there and should be spoken to, watched or charged." Dozens of Americans have been to Syria to take part, one way or another, in the civil war, Comey says.

While some compare the situation to the experience of those who met up with terrorists in Afghanistan, Comey said that what's happening in Syria is more worrisome for two reasons. First, he said, the people going to Syria are from more diverse backgrounds and of varying ages. And second, there's a big outflow of refugees, with people seeking asylum, so it's harder to keep track of who's entering and leaving the country.

"People, including Americans, can go to Syria and learn about dangerous techniques, and it's easy to get in and get out. It's a challenge to identify people with bad intent and keep track of them, but we're spending an enormous amount of time on it," he said.